The invention relates generally to ink jet printers. More particularly, the invention relates to a method for laser ablating an ablatable material to form a uniform nozzle structure having substantially parallel ink delivery paths.
Precise placement of ink drops onto a print medium is dependent upon uniformity of the nozzle structure among a plurality of nozzles formed in a film from which nozzle plates are formed. Current laser ablation techniques tend to form nozzles which are not parallel to one another. That is, the ink drops expelled from the nozzles do not follow parallel trajectories from nozzle to nozzle. Converging or diverging ink droplets result in less than optimal print quality.
What is needed, therefore, is a laser ablation system and method operable to form uniform nozzle structure in an ablatable material so that ink drops expelled from each nozzle follows a substantially parallel trajectory from nozzle to nozzle.
The foregoing and other needs are provided by a laser ablation system and method for forming ink delivery structure in an ablatable material. According to the invention, a method for fabricating an ink delivery structure in an ablatable material utilizes a laser ablation system including a laser for transmitting a laser beam. The laser ablation system also includes a field lens unit coupled to a field lens unit actuator, a projection lens, a mask disposed between the field lens unit and the projection lens, the mask having a first formation portion and a second formation portion, and a mask adjustment device for positioning the first or the second formation portion of the mask relative to the field lens unit. The field lens unit is set to a first position relative to the projection lens with the field lens unit actuator and the first formation portion of the mask is positioned relative to the first position of the field lens unit. The ablatable material is then partially ablated with the laser beam through the first formation portion of the mask. The field lens unit is then set to a second position relative to the projection lens, and the second formation portion of the mask is positioned relative to the second position of the field lens unit. The ablatable material is then ablated with the laser beam through the second formation portion of the mask. A substantially diverging laser beam structure is transmitted through the projection lens due to the second position of the field lens unit, resulting in a substantially uniform nozzle structure.
According to the invention, a uniform nozzle structure is formed in the ablatable material by repositioning a field lens unit during various ablation steps, optimizing the ejection of ink and corresponding drop placement on the print medium. Furthermore, the lifetime of the projection lens is not compromised due to the repositioning of the field lens unit and associated focal point. That is, when the field lens unit and associated focal point is moved closer to the projection lens, a portion of the mask is utilized which masks enough of the laser energy to substantially compensate for the shorter distance between the focused beam and the projection lens, thereby reducing the laser energy impacting on the projection lens.